/* 使用接口来限定/约束一个函数 */
(() => {
  // 函数类型
  interface searchInterface {
    (source: string, str: string): boolean 
  }

  const s: searchInterface = function (s1: string, s2: string): boolean {
    
    return s1.includes(s2)
  }
  console.log(s('abcdef', 'bc'))

})()